Pretightening-force-free variable friction inerter

The utility model provides a non-pretightening force variable friction inerter which comprises a sleeve, a ball nut is rotatably installed in the sleeve, a first guide cylinder and a second guide cylinder which are connected with the sleeve in a sliding mode are arranged on the two sides of the ball nut respectively, and a rotary friction flywheel is fixedly installed at the end of the ball nut. The two sides of the rotating friction flywheel abut against the first guide cylinder and the second guide cylinder respectively, a ball screw connected with the ball nut in a matched mode is installed on the ball nut, the two ends of the ball screw are fixedly connected with a first shaft rod and a second shaft rod which are in sliding connection with the sleeve respectively, the first shaft rod is sleeved with a first spring, and the second shaft rod is sleeved with a second spring. According to the inerter, positive pressure is provided for the rotating friction flywheel by compressing the first spring or the secon